It is viable in IT, just as with any single mastery though, stats will be low, so you will need to be careful as appropriate. Most mobs can be dealt with by electrical burn (DW or DR), then Sands of Sleep. Enough EBD gear exists for this to work, though it will take longer without resist reduction of course. Nightmare is able to grab the aggro of a lot of bosses, which will make those boss fights easier.